Apparatus for discharging fluid material from a container



Se t. 17, 1968 H. KLETSCHKE 3,401,843

APPARATUS FOR DISCHARGING FLUID MATERIAL FROM A CONTAINER Filed June 2,1966 1 j y M m 2 r J ,2 V j B 777 d 3 i FIG.| 4 1 6 FIG. 3 FIG. 2

INVENTOR. HANS KLETSCHKE aBAaAJZ M ATTO EY United States Patent 5Claims. (C1,. 222-363) ABSTRACT OF THE DISCLOSURE This invention relatesto improvements in apparatus for discharging material in fluid form froma container. By -material in fluid form is meant a fluid or a finelydivided solid or a mixture thereof The apparatus comprises areciprocatable piston, which partially rotates during reciprocation, andwhich has a recessed portion protruding into a container when the pistonis at the top of its stroke and being aligned with an outlet in acylinder, in which the piston reciprocates, when the piston is at thebottom of its stroke. Material is fed from the container into therecess, and from the recess into the outlet, by the action of pressureprevailing in the container or, in the absence of pressure in thecontainer, by the action of gravity.

Apparatus for the quasi-continuous discharge of gaseous, liquid and/orsolid substances from containers is known. With such apparatus a certainamount of the medium which is to be discharged is periodically removedfrom the container and conveyed as required. The interior of thecontainer may be under a pressure in addition to the gravitationalpressure of the contents. The discharge apparatus may have rotarypistons with axial recesses, or pistons which reciprocate in a cylinder.

As compared with a discharge apparatus having rotary pistons, anapparatus with recipricating pistons has the advantage that there isless difiiculty in sealing oif the piston where high pressuredifferences exist. Furthermore, rotary pistons must be of considerablesize when substantial quantities must be discharged, whereas anapparatus with reciprocating pistons is of relatively small size evenfor a large discharge capacity. Thus, piston slides are known in whichthe sealing means is an axially movable piston whose control surfaceupon opening exposes slots in the wall of a cylinder and thus provides apassage. In the case of piston slides, two pistons preferably arearranged one behind the other and the inflow of the medium to bedischarged takes place between these pistons. It is a disadvantage ofpiston slides, particularly when discharging suspensions of solidsubstances in liquids, that solid matter easily penetrates beneath thepistons and is there compressed. However, constructions are also knownin which this detrimental penetration is avoided. In the case of allpiston slides and similar constructions there is nevertheless theproblem of wear, which particularly occurs to a substantial extent inthe case of discharging the above mentioned suspensions of solids inliquids. Moreover, piston slides are unsuitable when substantialpressure differences must be overcome.

The present invention provides an apparatus for discharging material influid form from a container, as hereinbefore defined, the apparatusincluding a piston arranged to reciprocate, with partial rotation, in acylinder and during part of its stroke to project from the cylinder, thepiston having in the part thereof which so projects a recess to receivethe material, which recess is arranged to be sealed off on withdrawal ofthe piston into "ice the cylinder, and also including in the wall of thecylinder an outlet for the material with which the recess can be broughtinto register. The cylinder is attachable to an outlet of the containerin such a manner and the arrangement is such that the piston can projectinto the container and can execute its stroke while confining thecontainer with respect to the exterior. For use with a container underpressure, the apparatus is made duly pressure-resistant and has asuitable stufling box for the piston. The piston may be arranged, in itsstroke, to rotate through Apparatus according to the invention is veryreliable in operation and is subject to relatively little wear.

The invention is illustrated by way of example in the accompanyingdrawing, in which:

FIGURE 1 is an elevation of the relevant part of the apparatus, most ofwhich is shown in section, and

FIGURES 2 and 3 show different forms of the piston of FIGURE 1.

Referring to the drawing, the piston 7 is longer than the cylinder 4,and as shown in FIGURE 1 its upper end has an annular recess 8, which inan upper working position, shown in phantom at A, projects into acontainer of the type above described, while in a lower working positionB it is located with the recess in register with a side outlet 6 of thehousing including the cylinder 4. The piston is arranged to execute arotation of 180 during its movement from the lower to the upper workingposition and vice versa. The rotary cam stroke movement may be producedby means of a commercially available crank drive, eg of the Milton-Roydesign. A crank drive of the Milton-Roy design is shown for example inGerman Patent No. 1,104,786.

FIGURE 1 also shows the container in the form of a pressure pipe 1 witha rotary shaft 2, to which mixing and conveying arms are shown fixed,from which pipe a medium is to be discharged. The apparatus of theinvention is attached to a flanged outlet 3 of the pressure pipe 1. Thehousing including the cylinder 4, in its lower part carries a stuflingbox chamber 5 as well as the outlet 6. When the piston 7 is in the upperworking position the recess 8 fills with the medium in the pressurespace, and when the piston is in the lower working position the mediumis discharged through the outlet 6.

Instead of being annular as in FIGURE 1, the recess in the piston can bein the form of a transverse bore as in FIGURE 2 or of a blind hole as inFIGURE 3. The size of the recess should be selected so as to preservethe requisite mechanical strength of the piston, while giving anadequate delivery.

Both the cylinder and the piston of the apparatus of the invention areprovided with particularly wear-resistant surfaces, and may consist ofsteel which has been rendered wear-resistant by nitriding by one of theconventional methods, for example by the Sult-Inuz process or by theso-called mild nitriding process. A seal between the pressure chamberand the discharge chamber may be achieved by accurate grinding of thepiston into the housing bore. The use of piston rings is also possible.A seal from the exterior is provided by the above mentioned stuifing boxof conventional construction. When it is intended to discharge gaseswhich are under high pressure, the seals must be particularly efiicient.

The pressure difference between the space from which the medium isdischarged and the space into which it is transferred can beconsiderable and may, for example, be several hundred atmospheres. Theupper limit of pressure is determined only by the mechanicalload-bearing capacity of the material of the parts of the apparatus, andof the material being discharged. Depending on the operating conditions,working periods of at least several hundred hours can be achieved.Working periods of 1000 hours are generally attained, but periods of1500 hours or more have been reached.

The discharge of incompressible liquid and solid substances from acontainer by means of the apparatus of the invention is governed solelyby gravity acting on the substances. For this reason the maintenance ofa particular pressure in the container is in this case not essential.Where gases or liquified gases are to be discharged, the effect ofgravity is assisted by the expansion of the gases into space under lowerpressure.

The amount of gas, liquid or solid discharged depends on the size of therecess in the piston and on the number of strokes per unit time. It hasproved of advantage for the piston to perform to 120 strokes per minute,but higher and lower rates can be used. It is also possible to use theapparatus for sampling purposes, the piston being caused to execute asingle stroke as required.

The apparatus of the invention is primarily suited to the emptying ofpressure chambers in which reactions take place continuously. It isadvantageously used in the case of heterogeneous reactions in whichsolids suspended in liquids are reacted. The apparatus is particularlysuitable for this purpose since in view of the rotation of the pistonwhich is superimposed on the reciprocating movement, particularlyadvantageous wear characteristics are achieved. This is shown by theparticularly effective seal of the piston in the cylinder and by thelength of time that it remains adequate. Thus, an output rate of 100liters per hour has been achieved in discharging a cellulose suspensionfrom a digester at atmospheres gauge pressure, the piston having a cm.recess and executing 24 semi-rotary strokes per minute. The workingperiod of the cylinder was in that case between 1400 and 1800 hours.

A further advantage of the apparatus of the invention is that at eachstroke the piston penetrates relatively deeply into the container to bedischarged. In the case of suspensions this avoids non-representativeremoval of the contents, causing undesired separation of the componentsof a mixture, such as is liable to occur with all other known dischargedevices unless auxiliary means such as screws or stirrers are providedto prevent settling out in zones where this is liable to occur. There isalso little danger, when apparatus according to the invention has beenleft connected to a filled digester without being used for aconsiderable time, that the piston will become seized in the cylinder,because it is possible to bring the piston to the level of the bottom ofthe vessel and to leave it there. However, in some cases it still may beadvantageous to use an auxiliary device with the apparatus of theinvention, eg a device which assists the progressive movement of a loosesolid material. This can be achieved very simply by mounting a screw onthe cylinder.

The discharge apparatus of the invention is relatively inexpensivecompared with discharge equipment having rotary screws and of the sameoutput. I

It will be obvious to those skilled in the art that many modificationsmay be made Within the scope of the present invention without departingfrom the spirit thereof, and the invention includes all suchmodifications.

What is claimed is:

1. Apparatus for discharging material from a hollow container comprisinga cylinder having an open end thereof in communication with the hollowinterior of said container, piston means mounted in said cylinder toreciprocate and rotate with respect thereto, said piston means having asolid free outer end fitting within said cylinder to provide a sealtherewith, said piston means having recess means formed therein andspaced from said solid free end for receiving material therein, saidcylinder having an outlet formed therein, said piston means having adischarge position wherein said recess means is aligned with saidoutlet, and said solid free outer end of the piston is positioned insealing engagement with a cylinder portion intermediate said outlet ofsaid cylinder and said open end of said cylinder.

2. An apparatus according to claim 1 in which the piston means rotatesthrough in one stroke thereof.

3. An apparatus according to claim 1 in which the recess means has anannular shape.

4. An apparatus according to claim 1 in which the recess means is a borethrough the piston means.

5. An apparatus according to claim 1 in which the recess means is ablind hole in the piston means.

References Cited UNITED STATES PATENTS 2,220,466 11/ 1940 Tamrninga2.22365 X 2,721,004 10/1955 Schultz 222519 X 2,751,124 6/1956 Jones222340 X 2,780,984 2/1957 Kleeman 222-404 X 2,847,147 8/1958 Land222-365 X 3,164,304 1/1965 Jager et al 222-366 X STANLEY H. TOLLBERG,Primary Examiner.

